This invention relates to a brush arrangement.
Prior-art brush arrangements, also referred to as bristle or bristle tuft configurations, are intended for use in toothbrushes having a preferably electric drive mechanism for moving the brush arrangement relative to a motion axis of the brush arrangement. This may involve a preferably oscillating rotary motion about the motion axis and/or a preferably oscillating back-and-forth motion or vibratory motion in the direction of the motion axis. The brush arrangement comprises a bristle carrier and a plurality of upstanding bristles or bristle tufts anchored to the bristle carrier. The tree bristle ends define a working face also referred to as cleansing face because typically an appreciable part of the cleansing action is performed by the free bristle ends. Preferred fields of application of the present invention include the elimination of the film coating teeth, that is, dental plaque, in particular during the cleaning of interproximal spaces. Devices optimized for this purpose are frequently referred to as interproximal brushes.
For a long time only inadequate devices have been available for the cleansing and care of interproximal spaces unless performed by a dentist. Improvements have been sought by toothbrushes equipped with movably drivable brush arrangements. By way of example, DE 33 925 shows a toothbrush two hydrodynamically rotatable bristle carriers arranged side by side parallel to the axis. The slightly diverging bristles of the one bristle carrier form a working face in the form of a concave recess conforming to the convex outer shape of a molar, whilst the slightly diverging bristles of the other bristle carrier form a conical working face designed to enter into interproximal spaces. A similar suggestion is disclosed in U.S. Pat. No. 5,862,559. The toothbrush shown in this patent has a rotary brush arrangement with bristle tufts aligned parallel to the motion axis, the bristles thereof being suitably dimensioned in length so as to form overall an approximately conical working face designed to facilitate the cleaning of interproximal spaces. Another brush arrangement designed in particular for the cleaning of interproximal spaces is disclosed in EP 0 765 642. The brush arrangement which is adapted to rotate about a motion axis by means of an electric drive mechanism has its bristle tufts arranged in several concentric circles. The tufts of the outermost bristle circle are inclined in and in opposition to the direction of rotation in such fashion that they intersect a plane through the axis of rotation of the brush arrangement at an angle. This oblique position in the direction of movement is intended to improve the penetration of the bristles into the interproximal spaces during operation of the electric toothbrush, hence enhancing the dental cleansing effect.
It is an object of the present invention to provide a brush arrangement of the type referred to which affords ease of manufacture and provides further enhanced dental cleaning, in particular in the area of interproximal spaces, when used on a toothbrush having a drive mechanism for the brush arrangement.
To accomplish this object, the present invention proposes a brush arrangement with the features discussed herein below and a toothbrush with the features discussed herein below.
According to the present invention, provision is made for the brush arrangement to include bristles disposed in a spaced relationship to the motion axis, in particular eccentrically or concentrically, said bristles being inclined at an angle of inclination in the direction of the motion axis. Conveniently, the bristles are grouped in bristle clusters or bristle tufts which are aligned so that the center-of-gravity axes or axes of symmetry of the bristle tufts are inclined towards the motion axis. The inward inclination as disclosed in the invention has the effect that the free bristle ends of the inclined bristles tie closer to the motion axis than the bristle anchor points in the area of the bristle carrier. This enables a high bristle density advantageous for producing a good cleansing effect to be obtained in the area of the preferably rounded free ends, that is, in the area of the cleansing face or working face, while enabling, in the area of the fastening points e.g. anchor points on the bristle carrier, individual bristle tufts to be set at a sufficiently wide lateral distance to each other. Hence it is possible for each fastening points e.g. anchor point of a bristle tuft to be surrounded by sufficient bristle carrier material, to ensure its secure retention on the bristle carrier. When the anchor wire tufting technique is employed for manufacture, it is possible to set the hole mounts required to receive the bristle tufts at a sufficient lateral distance to each other so that tufting can be accomplished readily using conventional fixtures. In a preferred further aspect, for example, the inwardly oriented oblique position of bristles has the beneficial effect that the working or cleansing face is at least 20% smaller than the anchor area of the bristle carrier provided for tufting, with the size of the cleansing face preferably amounting to between about 50% and about 80% of the size of the anchor area. The term anchor area as used herein is understood to mean the surface area bounded by an envelope enclosing the bristles or bristle tufts in their base region close to the bristle carrier.
The angle of inclination or the oblique position may be selected so that the individual bristle tufts are able to bear against each other in the area of the working or cleansing face. This may significantly reduce bristle wear since it counteracts buckling.
Owing to the inwardly oriented oblique position or inclination of peripheral bristles or bristle tufts it is furthermore possible to produce a generally conical or frusto-conical array of bristles which facilitates introduction of the bristles into interproximal spaces. In contrast to conventional brush arrangements having bristles extending in substantially parallel alignment to each other, the oblique position has the added effect of causing the inclined bristles to respond more flexibly when subjected to axial loads, that is, loads parallel to the motion axis, so that the brush appears to exhibit a reduced axial stiffness. This may reduce or prevent the risk of gum injury as the brush arrangement is introduced into interproximal areas.
On a motion relative to the motion axis predetermined by the type of toothbrush, that is, in particular on a rotary oscillating motion about this axis, the oblique position has the beneficial effect that the individual bristles or bristle tufts of the brush arrangement conform themselves particularly well to the contours of the teeth bounding the interproximal space being worked and/or to the contour of the relevant gingival area, hence enabling the supra-gingival film (plaque) and the interproximal plaque to be removed more effectively. Owing to the invention arrangement of bristles or bristle tufts, a better cleansing operation can be accomplished of both punctiform (interproximal) and linear (gingival) areas of a person""s teeth.
The cleansing effect may be supported, where applicable, by a pulsating or vibrating reciprocating motion essentially parallel to the motion axis. This poking motion may be of advantage also without a simultaneous rotary motion being performed. DE 196 27 752 (which corresponds to U.S. Pat. No. 5,994,615) discloses an electric toothbrush which is particularly suitable for utilization in connection with brush arrangements of the present invention and which permits both an oscillating rotary motion about the motion axis and an oscillating back-and-forth motion parallel to the motion axis.
In a preferred further aspect the angle of inclination is in the range of smaller than about 15xc2x0, in particular in the range of between about 4xc2x0, and about 8xc2x0. These relatively small angles of inclination are sufficient to produce the ad vantages of the invention, enabling, in particular at angles of inclination of up to about 8xc2x0, the brush arrangement to be manufactured using conventional fixtures for tufting with anchor wire. The brushes can be tufted with a 0xc2x0 slope as for bristle tufts. Due to the oblique position limited to relatively small angles of inclination, it is furthermore possible to achieve rounding qualities higher than 90% for the free bristle ends.
In a further aspect provision is made for the brush arrangement to have at least one, preferably precisely one ring of bristles in which the bristles are arranged in an essentially circular array around the motion axis and are inclined in the direction of the motion axis in the manner described. Conveniently, the bristle ring arranged preferably concentrically with the motion axis is formed by several, in particular three, bristle tufts equally spaced apart circumferentially on the bristle carrier. Such a peripheral bristle ring provides the described frusto-conical outer contour of the bristle arrangement. The bristle tufts may be arranged symmetrically so that the axis of symmetry of the bristles or tufts coincides with the motion axis of the brush arrangement. As a result a uniform cleansing action is achievable on rotation about the motion axis and/or vibration along the motion axis.
A further feature is characterized in that the brush arrangement includes a center tuft of bristles arranged essentially concentrically with the motion axis and provided preferably in addition to a bristle ring surrounding the center tuft. This enables a variety of advantageous configurations to be implemented in which the properties of the brush arrangement in the center region, that is, in the region of the motion axis, differ from the properties in the surrounding peripheral area.
In particular provision may be made for the free ends of bristles in the area of the motion axis to protrude beyond the free ends of peripheral bristles, for example, by an amount of between about 0.5 mm and about 1.5 mm. This makes the center bristles the preferred choice for the cleansing of interproximal spaces, which operation is supported by a poking reciprocal motion along the motion axis and/or, where applicable, an oscillating rotary motion. The recessed, radially outer peripheral bristles may be used for working dental and gingival surfaces adjoining the interproximal spaces.
Hence a substantially convex, in particular conical or pyramidal working face may be implemented which may also be graduated. To increase the effective bristle length without incurring a reduction in brush stiffness in axial direction, provision may also be made for the brush carrier to have an elevation in the area of the motion axis, which is dimensioned such that the bristles in the area of the motion axis may be anchored above the level of peripheral bristles. For example, a central elevated platform of a height of between 1 mm and 2 mm may be provided on an otherwise plane, for example, disk-shaped bristle carrier section. With this construction, an essentially like free length of all the bristles of the array is achievable, while yet the bristles in the center area protrude beyond those on the periphery. Suitable bristle lengths, measured above the bristle carrier, Lie in the range from about 6.5 mm to about 8.5 mm, in particular at about 7.5 mm.
As an alternative or addition to the features relating to the bristle length and/or the shape of the working face, provision may also be made for the center bristles, that is, the bristles in the area of the motion axis, to be of greater hardness than the peripheral, eccentric bristles. The term hardness as used herein is understood to mean primarily the hardness perceivable by the user which, among other factors, is influenceable by the axial brush stiffness of the bristle material and/or the oblique position or inclination of bristles. In a preferred embodiment, the hardness of the bristles in the area of the motion axis is determined by a bristle strength of about 7xc2x12 mil, and/or the hardness of eccentric bristles is determined by a bristle strength of about 6xc2x12 mil. The dimension mil which indicates the bristle diameter corresponds to one thousandth of an inch equaling 0.0254 mm. Generally bristle diameters in the range of between about 4.5 to about 8 mil have proven in practice. In particular for reasons of hygiene and durability bristles formed from a plastics material are the preferred choice, particularly from PA 6.12 type nylon. However, it is also possible to fabricate part or all of the bristles from natural fiber.
The preferred embodiments of brush arrangements described in connection with the drawings are essentially configured so as to be symmetrical to the motion axis, the embodiment providing a center tuft having its center-of-gravity axis or axis of symmetry coincident with the motion axis. To enhance the cleaning action in combination with an oscillating motion of the brush arrangement (rotary and/or vibratory), provision may also be made for the axis of symmetry of the center tuft and/or the entire brush arrangement to be given a slight slope, for example, at an angle of inclination of the order of magnitude of between 2xc2x0 and 6xc2x0, in particular about 4xc2x0, with respect to the motion axis. As an alternative or addition, it is also possible to provide for a lateral offset of the axis of symmetry of the entire brush arrangement and/or of only the center tuft with respect to the motion axis, for example, by about 0.5 to about 1 mm. For example, on a rotation about the motion axis, an oscillating transverse motion which is superposed upon the rotary motion results in a direction transverse to the motion axis, which may contribute to supporting the cleansing effect.
The present invention further relates to a toothbrush which is of great advantage particularly for the cleaning of interproximal spaces and the removal of plaque. It comprises a movably drivable brush arrangement including a bristle carrier and a plurality of upstanding bristles anchored to the bristle carrier, and a preferably electric drive mechanism for moving the brush arrangement relative to a motion axis. By using brush arrangements according to the present invention, such a toothbrush may be upgraded in simple manner to a dental care device which is particularly effective for the cleansing of interproximal spaces and/or the removal of dental plaque. Conveniently, the brush arrangement is associated with a separate, exchangeable brush section on attachable to a handle section of the toothbrush as by plugging it on. A preferred embodiment of a toothbrush which enables the brush arrangement to oscillate about the motion axis in a rotating motion and to oscillate along the motion axis in a reciprocating motion is disclosed in DE 196 27 752 (which corresponds to U.S. Pat. No. 5,974,615 whose features relating to the toothbrush and the brush section shall be deemed to be incorporated by reference herein and to be a part hereof.
The features described and further features of the present invention will also become apparent, from the subsequent description of a preferred embodiment taken in conjunction with the claims and the accompanying drawings. It will be understood that the individual features may be implemented each for itself or in combination with several other features.